4x4 Not Engaging - No dash light

[phattyduck]

Charlie - thanks very much for the reply. I forgot the '99 Limited was different than the other '99 models, so I'm pretty sure I don't have a relay by the glove box. I was basing that assumption on some internet discussion of other '99 4WD systems (and my limited looking under the glove box). I acquired this from the estate of a neighbor who lived across the street from me. She was the original owner and other than routine maintenance I'm sure she never did any modifications. So it sounds like I need to pull the driver side kick panel off and take a look at the ECU there.

The most likely issue here is unplugged or dirty (non-working) switches. The '99/'00 Limited system uses switches in/on the transfer case that can stop working if not regularly used, along with the switch connected to the shifter button. Similar with the actuator and its internal position sensors - but you aren't even getting to that point (that would be a blinking 4WD indicator issue).

-Charlie

 

[TexasAggie91]

The most likely issue here is unplugged or dirty (non-working) switches. The '99/'00 Limited system uses switches in/on the transfer case that can stop working if not regularly used, along with the switch connected to the shifter button. Similar with the actuator and its internal position sensors - but you aren't even getting to that point (that would be a blinking 4WD indicator issue).

-Charlie

Thanks again Charlie for your insight. The lack of any 4WD lights is the perplexing part for me. I can't get any of the 4WD lights to come on under any scenario. I used the jumper wires to engage the front diff, took it off the jack stands and drove it to the end of our cul de sac and made several right turns engaging and disengaging the 4WD button but no lights came on. I read somewhere that sometimes helps, but nothing changed. Then on a straight portion of the road I put the transfer lever in 4H and then 4L (after putting the transmission in neutral). I went very slowly and did not turn the wheel but still no lights came on.

We're in TX so I'm sure the 4WD was rarely engaged. The prior owner had basic maintenance (i.e. fluid changes) done at a local quick lube place, but I did find one entry on the Toyota service website using the VIN. Back in 2010 the entry said "ADD was stuck in 4WD; disengaged 4WD via a vac line for ADD". I wouldn't be surprised if that was the last time she tried the 4WD. For the last 8 years it was kept in the garage and only driven a few times per year, so I'm trying to bring it back from hibernation. Thanks again for your help.

 

[TexasAggie91]

The saga continues, but at least I've got some new info. I mistakenly thought I'd checked the 20 amp 4WD fuse when in actuality I checked the 20 amp windshield wiper fuse that is located directly above it. One reason I made the mistake is that the 4WD fuse was missing. I looked at the fuse diagram on my computer and noted the 4WD fuse was the 4th slot down on the left, at the bottom of the left side and 20 amps. All that description fit the windshield wiper fuse when you count the blank slot that is at the top of the row (the blank slot wasn't included on the diagram I looked at). All that to say, I stuck a 20 amp fuse in the 4WD slot and now I have blinking 4WD lights in pretty much any scenario I've tried so far. If I disengage the 4WD button the lights stop blinking for a few seconds and then start blinking again. I'll do some more troubleshooting tomorrow (probably starting with the transfer case switches), but at least now I have power to the 4WD system. Felt like an idiot when I realized I'd checked the wrong fuse, but wasn't expecting a fuse to be completely missing.

 

[phattyduck]

That's good progress.

Keep in mind that even through it LOOKS like you are physically shifting something when you move the shifter from 2H to 4H position, there is nothing you are physically doing inside the transfer case. It is just actuating one of the position sensing switches on the transfer case. The computer then does the actual shifting. The only time something is physically happening in the case is the H-L shift.

I would continue to try shifting back and forth between various "High" positions to 'exercise' the actuator and see if that helps. It sounds like the same issue is happening again. Exercising it a bunch is a good first step.

As an aside, you likely have 12V on one of the VSVs in the front now. It is probably worth it to make sure that the front prop shaft spins freely when you have 2WD selected. It won't try to lock the front until it senses that the transfer case actuator is in the correct position.

Now the issue is most likely the position sensing in the transfer case actuator or something with the ADD system (more likely with the TC actuator).

-Charlie

 

[TexasAggie91]

Thanks Charlie - and sorry for the bad info earlier. I've worked on my own cars my whole life, but am new to the world of 4WD. I'd always admired this 4Runner from across the street and when the estate executor offered it to me for a song, I couldn't pass it up. I've changed the LBJ, outer tie rods, steering rack and rear gate struts with OEM parts and am now moving on to the 4WD issues. I've got all the parts for the timing belt, water pump, cam seals and front crank seal replacement, but wanted to try to get the 4WD operational first.

 

[2TH4IST]

You can take out the transfer case switches and depress the ball and try to clean it out with some brake cleaner. Do that a few times and see if you can get them to work. You can also do a continuity test before and after. This is cheaper then buying all 4 new switches.

 

[TexasAggie91]

Thanks for that suggestion. Cleaning switches with some brake cleaner certainly sounds cheaper than buying new switches, especially since I've been using OEM parts whenever possible. I've heard some of the switches are hard to get to, but if I need to buy some new tools to do so I'll spend money on tools instead of parts.

 

[TexasAggie91]

That's good progress.
I would continue to try shifting back and forth between various "High" positions to 'exercise' the actuator and see if that helps. It sounds like the same issue is happening again. Exercising it a bunch is a good first step.

I'm very happy to report this actually fixed the issue. I didn't think the odds were great that this would fix it after so many years of sitting idle, but it appears to have done the trick. I tried the 4WD button, the H4L and the L4L positions (with straight line driving for the H4L and slow straight line driving for the L4L) and the indicator lights all appear to work correctly. Sometimes there was a delay of about 5 seconds with blinking lights when engaging or disengaging the 4WD button while in H2, but the lights turned solid or turned off after the brief delay. I will be sure to exercise the different 4WD modes regularly to try to keep the components in working order. I'll plan on changing the transfer case fluid soon as well. Thanks again for your help!